The clash underscored the difficulty of ending violence in the country’s south despite the widely hailed conclusion over the weekend of Malaysian-brokered peace talks between the government and the 11,000-strong Moro Islamic Liberation Front.

At least four other smaller rebel groups threaten the peace in the south, including the Bangsamoro Islamic Freedom Movement, whose fighters were involved in Monday’s fighting.

Regional army spokesman Col. Dickson Hermoso said police backed by troops were on the way to arrest Bangsamoro Islamic Freedom Movement rebel commanders when the clash erupted in a vast marshland of southern Maguindanao province.

Police also came under fire Sunday when they attempted to arrest the rebel group’s commanders in another Maguindanao area.

Army troops launched artillery strikes and deployed two helicopter gunships after dozens of rebels were seen massing near two communities, prompting many villagers to flee to safety, military officials said.

Rebel spokesman Abu Misry said two fighters were wounded by army gunfire and shelling in the clashes. Government forces started the fighting and Misry said his group would retaliate by launching attacks against the military.

Misry’s group, which has a few hundred armed fighters, has opposed the peace talks and vowed to continue fighting for a separate Muslim homeland in the south in the predominantly Roman Catholic nation.

The conclusion of the Malaysian-brokered talks involving the Moro Islamic Liberation Front has been the most significant progress made over 13 years of negotiations to tame a tenacious insurgency that has left more than 120,000 people dead and crippled development in Muslim-populated southern regions that are among the poorest in the country.

Under the peace deal, the Moro insurgents agreed to end violence in exchange for broader autonomy. An existing five-province Muslim autonomous region is to be replaced by a more powerful, better-funded and potentially larger region to be called Bangsamoro, which would be secured by a force composed of former guerrillas.